Vlad is fine, but undertuned.
I guess people just odn't grasp the concept of 'life as resource'. Yes, vlad looses health for casting E, but he can gain lots of health from his Q and R. W costs health aswell, but also can give some. He also gains hp from building ap, and damage from building hp. While others have to manage their mana or heatbar, vlad needs to manage his health.
The tuneing isn't spot on atm, sure, but most people complain about the very concept of loosing health for casting a(unreliable) spell. But imo, that very concept has some potential that old vlad never really used, and it can create interesting gameplay. Right now, his sustain seems to restricted to properly compensate the health costs, his 'ebb and flow' of health seems to extreme, makeing him very hit or miss, and his choice of how much hp to spend seems a bit to limited, so he often ends dying befor the tide roles in via crimsion rush, or his opponents avoid the tied and abuse the following ebb. However, this isn't a issue of the concept, but the tuneing, so please try to differnciate between the two, as i think that most that complain about his healthcosts don't actually dislike the concept, but the state he's in because of his tuneing.